The present invention relates in general to clutches which are either manually or automatically adjustable to compensate for wear of the components therein, and in particular to an adjuster ring adapted for use in either type of such clutches.
It is well known to utilize a spring-loaded friction clutch to selectively connect a vehicle engine to a drive train of the vehicle. Such clutches typically include a plurality of driving components, such as a flywheel and an annular pressure plate, which are connected to the vehicle engine for rotation about an axis. An intermediate plate may also be provided between the flywheel and the pressure plate. Although they rotate with the flywheel, the pressure plate and the intermediate plate are also axially movable relative to the flywheel. Such clutches further include a plurality of driven components, such as one or more annular driven discs, which are connected to the vehicle drive train by means of an output shaft. The driven discs are interposed between the flywheel and each of the pressure plates, while the output shaft is oriented co-axially with the axis of rotation of the driving components. The driven discs are also axially movable relative to the output shaft and to the flywheel. As is well known in the art, the pressure plate is selectively moved axially toward the flywheel (typically by means of a lever system) so as to frictionally engage the driven disc or discs therebetween when it is desired to connect the vehicle engine to the drive train of the vehicle.
Generally, only predetermined portions of the faces of the driving and driven components of the clutch are designed to frictionally engage one another. These portions are usually covered by a fibrous or similar facing material. Such facing material is subject to wear from repeated usage. As wear occurs, the facing materials become thinner, and the relative distances of axial movement of the various driving and driven components of the clutch increase, as is well recognized in the art. Such increases are generally considered to be detrimental, since the clutch is usually designed to perform optimally for a single predetermined distance of axial movement. Consequently, modern clutches frequently include an adjuster ring which compensates for wear of the facing material in order to maintain the original predetermined distance of axial movement.
Such an adjuster ring typically includes a threaded outer circumferential surface which cooperates with a corresponding threaded inner circumferential surface formed on a cover attached to the flywheel. The adjuster ring pivotally supports the radially outermost ends of a plurality of levers. The levers are disposed adjacent the driving pressure plate. The radially innermost ends of the levers are retained in an axially movable clutch collar disposed about the output shaft. Rotation of the adjuster ring relative to the clutch cover causes the adjuster ring (as well as the radially outermost ends of the levers) to move axially toward the flywheel, thereby decreasing the relative distance of axial movement of the components of the clutch between engaged and disengaged positions. Thus, as wear occurs in the clutch as described above, the adjuster ring can be rotated to compensate therefor.
In the past, the adjuster ring had to be manually rotated within the clutch in order to achieve the desired compensation for wear. Such a manual adjuster ring included a plurality of lugs formed about the periphery thereof, which were adapted to cooperate with a lock strap removably secured to the clutch cover. The lock strap was inserted between two adjacent lugs in order to prevent rotation of the adjuster ring relative to the cover during use. Consequently, the lock strap had to be removed to permit an adjustment to be made. More recently, the adjuster ring has been automatically rotated by means of an automatic wear compensating device. Such an automatic adjuster ring included an internal threaded surface which cooperated with the automatic wear compensating device to rotate the ring as wear occurred. Both of such adjuster rings are in common use today. While both types of adjuster rings are useful, they are not interchangeable in a manner which permits them to function properly. As a result, clutch rebuilders are required to stock both types of adjuster rings in their inventories. It would be desirable, therefore, to provide a single adjuster ring which can be utilized in a manually adjusted clutch (in combination with a lock strap) or in an automatically adjusted clutch (in combination with an automatic wear compensating device).